1. Field of the Invention
The present invention relates to an air breather device of an automatic transmission for a motor vehicle.
2. Description of the Prior Art
In order to keep the inside pressure of the transmission at atmospheric level, a so-called air breather device is mounted to the transmission, which permits introduction of ambient air into the transmission or air discharge from the transmission into the open air in accordance with the pressure difference created between the inside of the transmission and the open air.
For clarification of the task of the present invention, one conventional air breather device for an automatic transmission will be outlined with reference to FIG. 6.
FIG. 6 shows a torque converter automatic transmission disclosed in "Toyota Service Manual for A-140E type automatic transmission" issued from Toyota Jidosha Co., Ltd. on August, 1982. In the drawing, numeral 1 denotes a transmission housing, and 2 denotes a converter housing. These housing 1 and 2 are integrally connected to form a monolithic construction as shown. Numeral 3 denotes a torque converter installed in the converter housing 2, and 4 denotes a transmission mechanism installed in the transmission housing 1. Denoted by numeral 5 is a reduction gear interposed between the transmission mechanism and a differential gear 6. Numeral 7 denotes an oil pump which is arranged between the torque converter 3 and the transmission mechanism 4. Numeral 8 denotes an air breather chamber formed above the oil pump 7, to which an air filter 9 is connected through a pipe.
However, because of its inherent construction, the transmission fails to provide the air breather chamber 8 with a sufficient capacity. As is known, when the capacity is insufficient, high load operation of the transmission sometimes induces that the lubricant oil in the transmission housing is blown off through the air filter 9.